The progress in the multifunctionality of recent, semiconductor integrated circuits causes an increase in the circuit scale. For example, recent progresses in the resolution and multifunctionality of liquid crystal display devices used in portable terminals such as smart phones and cellular phones have brought about an increase in the scale of RAMs (random access memories) and logic circuits integrated in driver ICs (integrated circuits) which drive liquid crystal display panels.
The increase in the multifunctionality and scale is inevitably accompanied by an increase in the number of external connection terminals. The increase in the number of external connection terminals restricts the size of the external connection terminals, causing a difficulty in the device mounting. The difficulty in the device mounting undesirably increases the variations in the contact resistances of external terminals and this may increase contact resistances at external connection terminals of semiconductor integrated circuits.
This problem is especially significant for semiconductor integrated circuits using a flipchip connection, for example, driver ICs connected with display panels. The reduction in the size of external connection terminals of a driver IC undesirably causes the difficulty in assembling the driver IC onto a display panel with a flip chip connection in a display device (or a display module) and undesirably increases the variance in the contact resistances between interconnections on the display panel and external connection terminals of the driver IC. This implies that some of display devices inevitably suffer from a high contact resistance.
One problem caused by the increase in the contact resistance at external connection terminals is reduction in the drive capacity of a power supply circuit which feeds a power supply voltage to internal circuits. The increase in the contact resistance at an external power supply terminal through which an external power supply voltage is fed to the power supply circuit undesirably decreases the voltage actually fed to the power supply circuit due to the voltage drop across the external power supply terminal, causing degradation of the drive capacity of the power supply circuit. A recent semiconductor integrated circuit with high multifunctionality and integration consumes a large amount of power, and therefore the degradation of the drive capacity of the power supply circuit may cause a malfunction of the semiconductor integrated circuit. The problem of the degradation of the drive capacity of the power supply circuit may be caused by a different reason other than the increase in the contact resistance at an external connection terminal, for example, a decrease in the external power supply voltage itself.
It should be noted that Japanese Patent Application Publication No. 2010-256968 A discloses a power supply regulator circuit which generates a desired voltage from a power supply voltage fed from a battery.